Annuloplasty rings are used to provide support to surgically corrected defects in natural valves of a patient's heart. The valves in the human heart, and in particular the mitral and tricuspid valves, include valve cusps or leaflets which are attached to the wall of the heart by fibrous chords. However, defects in the heart valve and surrounding tissue can reduce the efficiency of the heart in pumping blood. For example, if the annulus of a heart valve dilates due to disease, the valve cusps cannot completely close. This allows blood to regurgitate through the valve and greatly reduces the efficiency of the heart.
One technique of repairing a defective natural heart valve is to completely replace the valve. Valve replacements include both mechanical heart valves and bioprosthetic heart valves. However, such surgery requires the natural valve to be excised. In many instances it would be preferable to retain the natural valve by repairing the valve. For a number of reasons, it is desirable to retain the natural heart valve if possible.
A native valve repair procedure utilizing an annuloplasty ring is a desirable alternative to replacement valves in that the repair procedure does not require excision of the natural valve. Various types of annuloplasty rings are described in the prior art including rigid rings and flexible rings. For example, U.S. Pat. No. 5,061,277, issued Oct. 29, 1991 to Carpentier et al., entitled "FLEXIBLE CARDIAC VALVULAR SUPPORT PROSTHESIS" is an example of one such annuloplasty ring. Flexible annuloplasty rings allow the heart to follow a more physiological movement during systole and diastole. Additionally, the native mitral annulus is not a flat plane, and the anterior portion of the mitral annulus is curved. Such flexibility is particularly beneficial when the heart is operating at higher capacities. Traditionally, annuloplasty rings have a generally full annular configuration. The full annuloplasty ring is sutured to the tissue annulus of the natural heart valve. The ring provides support to the valve annulus or repaired valve to thereby maintain the shape of the repaired heart valve by preventing dilation of the annulus.
Recently, annuloplasty rings have been designed with a partial annular configuration. One such design is described in U.S. Pat. No. 5,041,130. Such a partial annular configuration may allow limited expansion of the natural annulus during diastole. The partial annular configuration has no anterior portion which allows the natural mitral annulus shape to be preserved in this area and to function naturally.
The anterior portion of the mitral annulus does not dilate with disease processes. Therefore, there is no need for the annuloplasty device to address this area. Not placing sutures in the anterior portion of the annulus eliminates the possibility of deforming or injuring, with sutures, the aortic valve leaflets which are in fibrous continuity with the anterior portion of the mitral valve. The decision to support the anterior portion of the annulus must be made by the surgeon on a case by case basis, and is frequently not apparent until the natural valve and surrounding cardiac anatomy is visibly inspected during surgery. Likewise, a partial ring can be used to repair the tricuspid valve to eliminate any negative effects of placing the suture in or near the AV-node.